Monday, March 14, 2011

On free VoIP

I've discussed Voice over IP before, and it's time to revisit it, to bring up certain ideas that I'll flesh out in forthcoming blog entries. Let's, for now, though talk about using voice over IP to talk to people for free.

Before we do that, let's rehash:

  • Voice over IP is a system for two way voice communication over the Internet, in a way that, to end users, resembles a telephone call.
  • Some telephone services, notably Vonage, actually route your calls over the Internet.
  • More typically, Voice over IP is implemented using tools like Instant Messenger clients.
  • There are standards for Voice over IP, notably an de-facto standard built around a protocol called SIP, and various proprietary or semi-proprietary implementations.
Interestingly, one way in which voice over IP is becoming popular is for video, not voice, communication! This is because most telephone networks have not implemented the systems needed to support standardized videophone calls, but have implemented Internet connectivity, where standards for video calls over IP exist. You may have heard of Facetime, an "app" for the iPhone that implements video calls - but only between users of Apple devices.

Now, the questions you need to ask have to do with your needs and expectations. Typical questions that will affect what you plan to use are:
  1. Do you need access to the telephone network? Are you expecting to be able to make calls to telephone numbers, and are you expecting to receive calls to a phone number? Are you willing to pay for the privilege?
  2. How geeky are you? Are you willing to set up a server for this?
  3. Are you happy making calls directly from your laptop or desktop computer, or would you rather use an actual telephone?
  4. Will you need this while you're on the move?
  5. Will you be able to reach your friends with this? Will they be able to reach you?
Here are some options to think about. Before you read on, be aware this is a US-centric article. Some of the information may apply to other countries, but certainly not all.

1. GMail

The GMail website (and ONLY the website!) includes a voice over IP client that's integrated with Google Talk and Google Voice. Critically, this client allows you to make and receive regular phone calls, as well as make calls to other GMail users. Calls within the US, and to other Google Talk users, are free. The system is implemented using the Adobe Flash plug-in.

The best part of the GMail system is that it works with regular phone calls. I've even used it to make International calls - you have to pay for those, but the rates are fairly low. You can receive calls if you've set up a Google Voice number.

While this works well, it doesn't integrate with any other Voice over IP systems. You can't call Skype and SIP users, for example. This is a common problem, as we'll get to in a moment. And it requires you sit with a desktop or laptop computer - you can't use it from an actual phone (well, you might be able to use some of the latest Android devices, I don't know, but it's going to be awkward.)

Let's answer the above questions about GMail:
  1. GMail provides access to the telephone network, the US network for free.
  2. You don't need to set anything up other than to install the Flash plug-in - and you probably have that already.
  3. There's just no way to use GMail outside of a computer.
  4. You can use GMail whereever you have computer access, but anywhere else you're out of luck. You can get around this, to a certain extent, using Google Voice to forward incoming calls to your cellphone, but people using only Google Talk will not be able to communicate with you that way.
  5. Virtually everyone today has a telephone number, so you can use it to reach almost your friends, as long as they're in the US.
If all you're after is a way to save money when making occasional calls to friends, or if you have a lot of friends who use Google Talk, then you should find GMail will work well for you.

2. Skype

Probably the single most popular voice over IP service in the world, Skype is a proprietary system that generally requires installation of the Skype client on any device that needs to make calls. The positive news though is that there's clients for virtually everything save for the simplest devices. From PCs to tablets and smartphones, there's an official Skype client

Skype is also well supported by third parties. You can buy third party Skype handsets, and even cordless phones that use wifi to communicate with the Internet.

Skype does support calls to and from standard phone numbers, but here things start costing money. To use Skype to call other numbers, you need to subscribe to its special SkypeOut service. There are multiple talk plans, and generally the rates are low, but not free. Receiving Skype calls requires a SkypeIn number, which, again, is a subscription number.

So what's the deal here? Let's answer those questions, as above:
  1. Skype provides access to the telephone network, at a price.
  2. You need to install a proprietary Skype client on the device(s) you plan to use Skype with, but otherwise there's nothing to set up.
  3. You can use Skype on a variety of different systems, even smartphones, where receiving and making calls is no different to receiving and making ordinary phone calls.
  4. Connectivity depends on location and provider. US cell companies, for example, do not allow you to use their Internet networks to make Skype calls. If you want to make or receive calls when not in range of Wifi, you'll need to subscribe to Skype's SkypeIn and SkypeOut services.
  5. As the most popular VoIP service, there's a good chance your friends are already using it. For those that aren't, you can consider using the SkypeIn/SkypeOut services. Like GMail, Skype isn't integrated with other VoIP services, although some other services are attempting to make their clients interoperate, with different degrees of success.
Skype is popular and free, and even if you don't want to make it your primary means of communication, it's worth installing the client and setting up an account for those occasions friends want to talk to you.

    3. "SIP"

    I've put this one in quotation markets because it's not as easy to pin down. There's no single SIP provider, although SIP networks generally interconnect - that is, if you have an address and your friend has an address, you can usually intercommunicate. Where do you get the SIP address? Well, various providers exist. Many, such as Ekiga, offer the basic service for free - the "making SIP calls from one SIP user to another" doesn't take up much of the provider's bandwidth as they just set up the call, the routing for the call itself goes directly between the users. Making outgoing calls to the telephone network, however, is where things get more hairy.

    If you want to play with SIP, without spending a penny, go get yourself to and You'll get both a client to run on your PC, and a free SIP account. Now, let's see what the deal is with SIP by answering the above questions.

    1.  SIP itself is just a protocol, but various providers provide access to the telephone network, almost always at a price. I'm not aware, today, of anyone that offers outgoing calls for free, although some services offer incoming calls for free. is one of them.
    2.  SIP can be convoluted to set up and there are never any guarantees. This is because NAT, the system used to deal with the fact your ISP only gives you one address to cover all the devices in your home, does not work well with SIP. In certain circumstances, you will need a virtual PBX to route SIP calls. I don't want to scare you, you may find that it "just works" if you have the right type of router and your free SIP address provider has something called a STUN server, but you can't assume anything.
    3. SIP is a universal, open, standard and clients exist for everything from PCs to smartphones. Some manufacturers even make "Wifi phones" that can be programmed with a SIP account. Devices exist that allow you to hook up any phone to a computer network and have it be reachable over SIP. Unquestionably, it has the best hardware support of anything described here. Software support is superb. For Android devices, I recommend Linphone - you can download it from the Android Market.
    4. Connectivity is somewhat worse than Skype's right now. Calling over 3G is hit and miss even with networks that don't downright ban it, and you can't guarantee a free SIP service will work in a location with Wifi either, due to the issues with NAT. (Non-free SIP services may not have the problem, if they support proxies.)
    5. As the only real "standard" version of VoIP, SIP's userbase will grow over time, but the technical problems with the standard means it's likely to remain a niche system until IPv6 becomes popular and eliminates the need for NAT.
    SIP appears to have Google's attention right now, with the release of an (admittedly not terribly useful) SIP client in Gingerbread. Many of us are hoping Google will add SIP to its Google Voice service soon, it appears to be experimenting with the concept.

    SIP can be obtained free of charge, but you may find it just doesn't work in your environment. It costs nothing but time to check. It's probably better, for now, treated as a great way to create internal phone networks.


    There are, of course, many pay-to-use VoIP systems, from MagicJack to Vonage, that might better suit you depending on your needs. And as I'll explain in a forthcoming article, while there are many issues with SIP right now, it can work very well if you're interested in using it as an in-house communication system. We'll talk about that soon.

    1 comment:

    1. Don't forget about XMPP. With Jingle, it's a fine VOIP system, and so much more. :-)